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We consider leptogenesis in scenarios with many neutrino singlets. We find that the lower bound for the reheating temperature can be significantly relaxed with respect to the hierarchical three neutrino case. We further argue that the upper…

High Energy Physics - Phenomenology · Physics 2008-11-26 Marc-Thomas Eisele

Neutron stars (NSs) are powerful factories for new particles with masses up to the 100 keV range. These compact stars contain significant populations of charged particles, notably protons, electrons and muons. We calculate the emission…

High Energy Physics - Phenomenology · Physics 2026-05-26 Damiano F. G. Fiorillo , Alessandro Lella , Georg G. Raffelt , Nudzeim Selimovic , Edoardo Vitagliano

The out-of-equilibrium character of active systems is often twofold, arising from both the activity itself and from non-reciprocal couplings between constituents. A well-established measure to quantify the system's distance from equilibrium…

Statistical Mechanics · Physics 2026-02-13 Kim L. Kreienkamp , Sabine H. L. Klapp

The Asymptotic Safety scenario predicts that the deep ultraviolet of Quantum Einstein Gravity is governed by a nontrivial renormalization group fixed point. Analyzing its implications for cosmology using renormalization group improved…

High Energy Physics - Theory · Physics 2015-05-20 Alfio Bonanno , Martin Reuter

We investigate a class of universes in which the weak interaction is not in operation. We consider how astrophysical processes are altered in the absence of weak forces, including Big Bang Nucleosynthesis (BBN), galaxy formation, molecular…

Astrophysics of Galaxies · Physics 2018-03-14 E. Grohs , Alex R. Howe , Fred C. Adams

By using entropy and entropy production, we calculate the steady flux of some phenomena. The method we use is a competition method, $S_S/\tau+\sigma={\it maximum}$, where $S_S$ is system entropy, $\sigma$ is entropy production and $\tau$ is…

Statistical Mechanics · Physics 2016-07-26 Yong-Jun Zhang

Neutrino-matter interactions play a key role in binary neutron star mergers. Thermodynamics conditions at the surfaces where neutrinos decouple from matter influence neutrino spectra, ultimately affecting the evolution of the remnant and…

The emerging field of stochastic thermodynamics extends classical ideas of entropy, heat and work to non-equilibrium systems. One notable finding is that the second law of thermodynamics typically only holds after taking appropriate…

Statistical Mechanics · Physics 2024-02-27 Paul C Bressloff

We point out that in scenarios with a low reheating temperature $T_R << 100$ MeV at the end of (the last episode of) inflation or entropy production, the abundance of sterile neutrinos becomes largely independent of their coupling to active…

High Energy Physics - Phenomenology · Physics 2009-11-10 Graciela B. Gelmini

We review what is known about the contributions to the final entropy from the different stages of a relativistic nuclear collision, including recent results on the decoherence entropy and the entropy produced during the hydrodynamic phase…

Nuclear Theory · Physics 2009-11-18 R. J. Fries , T. Kunihiro , B. Müller , A. Ohnishi , A. Schäfer

We sketch the average behaviour of the temperatures and densities of the main components of the $\Lambda$CDM universe after inflation. It is modelled as a perfect fluid with dark energy associated with the macroscopic effect of conformal…

High Energy Physics - Phenomenology · Physics 2014-10-15 Natacha Leite , Alex H. Blin

We study particle production and the corresponding entropy increase in the context of cosmology with dynamical vacuum. We focus on the particular form that has been called "running vacuum model" (RVM), which is known to furnish a successful…

General Relativity and Quantum Cosmology · Physics 2020-02-14 Joan Sola , Hao Yu

The thermalization process is studied in an expanding parton gas using the Boltzmann equation with two types of collision terms. In the relaxation time approximation we determine the criteria under which a time-dependent relaxation time…

High Energy Physics - Phenomenology · Physics 2009-09-25 H. Heiselberg , X. N. Wang

The neutrino asymmetry in the early universe plasma, $n_\nu - n_{\bar \nu}$, is calculated both before and after the electroweak phase transition (EWPT). The leptogenesis before EWPT within the standard model is well known to be driven by…

Cosmology and Nongalactic Astrophysics · Physics 2017-05-05 Maxim Dvornikov , Victor B. Semikoz

The effects of viscosity on the space time evolution of QGP produced in nuclear collisions at RHIC energies have been studied. The entropy generated due to the viscous motion of the fluid has been taken into account in constraining the…

Nuclear Theory · Physics 2011-07-14 Sukanya Mitra , Payal Mohanty , Sourav Sarkar , Jan-e Alam

We study nonequilibrium thermodynamic properties of a driven one-dimensional quantum fluid by combining nonlinear Luttinger liquid theory with the quantum kinetic equation. In particular, we derive an entropy production consistent with the…

Mesoscale and Nanoscale Physics · Physics 2019-10-09 Edvin G. Idrisov , Thomas L. Schmidt

High center-of-mass electromagnetic~(EM) interactions could produce decaying heavy leptons and hadrons, leading to neutrino generation. These processes might occur in the most extreme astrophysical scenarios, potentially altering the…

High Energy Astrophysical Phenomena · Physics 2025-11-27 Gaetano Di Marco , Rafael Alves Batista , Miguel A. Sánchez-Conde

Dark Matter (DM) density is reduced if entropy production takes place after DM particles abundance is frozen out in the early universe. We study a possibility of such reduction due to entropy production in the electroweak phase transition…

High Energy Physics - Phenomenology · Physics 2022-02-01 Arnab Chaudhuri , Maxim Yu. Khlopov , Shiladitya Porey

The notion of inflation (past or present) in standard cosmological models is shown to be a consequence of a sufficiently high second law entropy production from the internal heating of the universal expansion. The longitudinal viscous…

General Relativity and Quantum Cosmology · Physics 2007-05-23 T. Sakai , A. Widom , Y. N. Srivastava

We show that the entropy of cosmological perturbations originating as quantum vacuum fluctuations in the very early universe, including the contribution of the leading nonlinear interactions, can be viewed as momentum space entanglement…

High Energy Physics - Theory · Physics 2020-11-12 Suddhasattwa Brahma , Omar Alaryani , Robert Brandenberger